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2-Lever vs 3-Lever Mortice Lock: Difference and Uses
Posted by National Lock Supply on Apr 25th 2023
A 3-lever mortice lock has one more lever in its lock case than a 2-lever lock, so it has more key combinations and is harder to pick, but both are low-security locks meant for interior doors. In the UK, only 5-lever (or higher) mortice locks can meet BS 3621 for external doors. In the US, commercial mortise locks use pin tumbler cylinders and are graded under ANSI/BHMA A156.13, not by lever count.
What is a lever lock?
A lever lock (lever tumbler lock) uses a stack of flat, pivoting metal levers, each with a slot called a gate. The key lifts every lever to a precise height so the gates line up and the bolt stump can slide through, letting the bolt move. If any lever is at the wrong height, the bolt stays blocked. Lever count is the number of these plates inside the case.
What is the difference between a 2-lever and a 3-lever mortice lock?
The difference is the number of levers the key must lift. More levers mean more possible key combinations (differs) and tighter tolerances, which makes a lock harder to pick or to open with a wrong key. Both 2-lever and 3-lever locks are generally treated as privacy or low-security locks for interior doors.
| Feature | 2-lever mortice lock | 3-lever mortice lock | 5-lever BS 3621 lock |
|---|---|---|---|
| Levers | 2 | 3 | 5 or more |
| Typical use | Interior privacy (cupboards, bedrooms, bathrooms) | Interior doors, low-security use | External doors, insurance-grade |
| Meets BS 3621 | No | No | Yes, when Kitemarked |
| Key differs | Fewest | More than 2-lever | Highest of the three; BS 3621 requires at least 1,000 |
Is a 3-lever mortice lock secure enough for an external door?
No. A 3-lever mortice lock cannot be Kitemarked to BS 3621, and UK insurers commonly ask for a BS 3621 lock on final exit doors. To meet BS 3621 a lock needs at least 5 levers with at least 1,000 key differs, plus anti-pick and hardplate protection and a minimum bolt throw. Treat 2-lever and 3-lever locks as interior-door hardware.
This post covers the lever-count question because that is how UK mortice locks are rated. If you are buying for a US building, read the next section.
What should US commercial buyers look for instead?
US commercial mortise locks do not use lever tumblers. They use a pin tumbler cylinder (conventional or interchangeable core) that operates a steel lock case, and they are rated under ANSI/BHMA A156.13, which sets operational and security grades; Grade 1 is the highest. So the questions to ask are the grade, the function (office, storeroom, classroom, entrance) and the cylinder type, not the lever count.
One source of confusion: Schlage mortise model numbers such as L9050P 06A or 06N use "06" to name the lever handle design, and "A" and "N" name the trim (rose or escutcheon). Those are ordinary lever handles on pin tumbler mortise locks, not lever tumbler locks. Examples:
- Schlage L9050P 06A office and inner entry mortise lock
- Schlage L9060P 06A apartment entrance mortise lock
- Schlage L9040 06A bath/bedroom privacy mortise lock
Browse all mortise locks. To size or replace the cylinder, see the mortise cylinder sizes and cams guide.
Mortise lock vs lever lock: what is the difference?
"Mortise" describes how the lock is installed: the lock case sits in a pocket cut into the door edge. "Lever" describes how the lock is keyed: levers inside the case. A mortice lock can be lever-operated (UK sashlocks and deadlocks) or pin tumbler operated (US commercial mortise locks). The terms are not opposites.
FAQ
What is a 2-lever lock used for?
Interior privacy and low-risk doors, such as cupboards or internal rooms. It offers the fewest key combinations and is not meant for doors where security matters.
Is a 3-lever lock better than a 2-lever lock?
Yes, slightly: one more lever means more differs and tighter tolerances. It is still a low-security lock and does not meet BS 3621.
Do 2-lever and 3-lever locks meet insurance requirements?
Not on external doors in the UK, where insurers commonly require BS 3621 locks, which need at least 5 levers. Check your policy wording.
Are US mortise locks lever locks?
No. They use pin tumbler cylinders and are graded under ANSI/BHMA A156.13. "Lever" in a US model name refers to the handle style.
Official sources
Grading for US mortise locks is defined by ANSI/BHMA A156.13 (Builders Hardware Manufacturers Association). For the BS 3621 lever requirements, see this BS 3621 explainer.
Next step
Shop commercial mortise locks or request a quote at get a quote. Orders placed before 3:00 p.m. ET ship the same business day after card approval, and ground shipping is free on orders of $450 and up. Call 718-814-6300 and we will match the function and grade to your door.